class_docstr: Cross validation mutator, withhold a fold.
class_docstr_tok: ["Cross","validation","mutator",",","withhold","a","fold","."]
code: def add_cmdline_args(
      cls, parser: ParlaiParser, partial_opt: Optional[Opt] = None
  ) -> ParlaiParser:
      super().add_cmdline_args(parser, partial_opt)
      agent = parser.add_argument_group(
          "KFoldWithholdOnTrainMutator args"
      )
      agent.add_argument(
          "--k-fold",
          type=int,
          help="the number of k-fold",
      )
      agent.add_argument(
          "--held-fold",
          type=int,
          help="the current fold reserved from training",
      )
      return parser
  
file_path: ParlAI/projects/trollhunting/mutators/k_fold.py
imports: from typing import List, Optional
  from parlai.core.message import Message
  from parlai.core.mutators import ManyEpisodeMutator, register_mutator
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.utils.data import DatatypeHelper
  import hashlib
  import parlai.utils.logging
label_desc: Use image node_id 1 for calling the KFoldWithholdOnTrainMutator obj's underlying member method code with example usage: obj.add_cmdline_args(cls, parser, partial_opt) and returns: parser